The use of weldable Super Martensitic Stainless Steel (SMSS) started at the end of 1990’s. The material is attractive for corrosive hydrocarbon service due to the resistance to CO2 corrosion and low cost compared to duplex stainless steel. SMSS is sensitive to Sulfide Stress Cracking (SSC) and Stress Corrosion Cracking (SCC), and must be tested for both mechanisms. Due to the lack of commonly accepted limits in international standard (NACE(1) MR0175 / ISO(2) 15156-3), internal qualification testing has been performed. During the qualification there has been many lessons learnt and the test procedure has developed over the time as new knowledge has been acquired. An important effect is the materials response to pipeline laying procedure and how this has to be accounted for during testing and interpretation of the test results. Inter Granular Stress Corrosion Cracking (IGSCC) has also occurred and countermeasures have been implemented. The paper gives a historical overview of the challenges that have been encountered and how these challenges have been solved.

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